| 闽西南永定大坪辉长岩脉的年代学、地球化学特征及地质意义 |
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| 引用本文： | 王锦荣,吕新彪,张建平,林晓晖,王继林,林香.闽西南永定大坪辉长岩脉的年代学、地球化学特征及地质意义[J].地球科学,2021,46(1):73-86. |
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| 作者姓名： | 王锦荣 吕新彪 张建平 林晓晖 王继林 林香 |
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| 作者单位： | 中国地质大学资源学院,湖北武汉 430074;中国冶金地质总局第二地质勘查院,福建福州 350108;中国地质大学资源学院,湖北武汉 430074;中国冶金地质总局第二地质勘查院,福建福州 350108;中国冶金地质总局二局,福建福州 350108;中国冶金地质总局山东局测试中心,山东济南 250014;福建省闽北地质大队,福建福州 350002 |
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| 基金项目： | 国家重点研发计划"深地资源勘查开采"专项;华南重点矿集区稀有稀散和稀土矿产调查项目 |
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| 摘 要： | 南岭地区湘南-赣南-粤北-闽西南近东西向的岩浆岩活动带在年龄、成因、动力学背景等方面一直存有争议.以福建西南部永定地区的大坪辉长岩脉为研究对象，在详细的野外工作及镜下岩相学观察的基础上，对其开展了斜锆石U-Pb同位素定年、全岩主微量元素含量以及Sr-Nd同位素比值的测试工作.获得同位素年龄为184.0±6.5 Ma，表明岩浆活动为早侏罗世.其地球化学特征具有高碱高钾的特点，无Nb，Ta的正异常，(87Sr/86Sr)i初始值变化在0.708 0~0.709 0之间，εNd(t)值在-3.6~-3.0之间，显示辉长岩脉起源于富集岩石圈地幔的部分熔融，未经历过壳源物质的AFC作用.该地区同时发育有双峰式火山岩及A型花岗岩，表明在早侏罗世包括永定在内的该岩浆带处于拉张的动力学背景，软流圈上涌，加热EMII型富集岩石圈地幔，分别形成了藩坑组玄武岩和永定大坪辉长岩脉.
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| 关 键 词： | 闽西南 永定大坪 辉长岩脉 岩石地球化学 |
| 收稿时间： | 2019-10-16 |
Geochronology,Geochemistry and Geological Significance of Gabbros from Yongding Daping Area,Southwest Fujian |
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| Wang Jinrong,Lü Xinbiao,Zhang Jianping,Lin Xiaohui,Wang Jilin,Lin Xiang.Geochronology,Geochemistry and Geological Significance of Gabbros from Yongding Daping Area,Southwest Fujian[J].Earth Science-Journal of China University of Geosciences,2021,46(1):73-86. |
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| Authors: | Wang Jinrong Lü Xinbiao Zhang Jianping Lin Xiaohui Wang Jilin Lin Xiang |
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| Affiliation: | (Faculty of Earth Resources,China University of Geosciences,Wuhan 430074,China;The Second Geological Institute of China Metallurgical Geology Bureau,Fuzhou 350108,China;The Second Bureau of China Metallurgical Geology Bureau,Fuzhou 350108,China;The Testing Center of Shandong Bureau of China Metallurgical Geology Bureau,Jinan 250014,China;Brigade in Northern Fujian,Fuzhou 350002,China) |
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| Abstract: | The age,petrogenesis and geodynamic background of the igneous rock belt across southern Hunan,southern Jiangxi,northern Guangdong and southwestern Fujian,have been controversial in last decades. In this paper,new gabbro samples from Daping of Yongding area in southwestern Fujian are studied to discuss related problems. Based on field work and microscopic petrographical observation,baddeleyite U-Pb isotope age,whole rock major and trace elements content,and Sr-Nd isotoperatios are acquired. The obtained isotopic dating result is 184.0±6.5 Ma,which indicates that the time of magmatism is in early Jurassic. Whole rock data show that these gabbros are high K2O and high K2O+Na2O,no Nb and Ta positive anomalies,(87Sr/86Sr)i value are between 0.708 0 and 0.709 0,εNd(t) value are from -3.6 to -3.0. Geochemistry data prove that gabbro originated from partial melting of enriched lithospheric mantle and had not experienced AFC process. At the same time,there are bimodal volcanic rocks and A-type granites formed in same area,indicating a extension dynamic background in Early Jurassic,enriched lithospheric mantle has EMII characteristics and been heated by the upwelling of as the nosphere mantle,their melts formed Yongding Daping gabbros and Fangkeng Formations basalt respectively. |
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| Keywords: | Southwestern Fujian Yongding Daping gabbro petrogeochemistry |
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